Not applicable.
1. Field of the Invention
The present invention relates generally to disk drives, and in particular to a spindle motor including a stator with magnetic flux guides.
2. Description of the Prior Art
The typical hard disk drive includes a head disk assembly (HDA) and a printed circuit board assembly (PCBA) attached to a disk drive base of the HDA. The head disk assembly includes at least one magnetic disk, a spindle motor for rotating the disk, and a head stack assembly (HSA) having an actuator assembly having at least one transducer head, typically several, for reading and writing data to and from the disk. The printed circuit board assembly includes a servo control system in the form of a disk controller for generating servo control signals. The head stack assembly is controllably positioned in response to the generated servo control signals from the disk controller. In so doing, the attached heads are moved relative to tracks disposed upon the disk.
The head stack assembly includes an actuator assembly, at least one head gimbal assembly, and a flex circuit cable assembly. A conventional xe2x80x9crotaryxe2x80x9d or xe2x80x9cswing-typexe2x80x9d actuator assembly typically comprises an actuator body that rotates on a pivot assembly between limited positions, a coil portion that extends from one side of the actuator body to interact with one or more permanent magnets to form a voice coil motor, and one or more actuator arms that extend from an opposite side of the actuator body. A head gimbal assembly includes at least one transducer head, sometimes two, which is distally attached to each of the actuator arms. The actuator assembly includes the actuator body that has a bore and a pivot bearing cartridge engaged within the bore. The head gimbal assembly and the flex circuit cable assembly are attached to the actuator assembly.
The spindle motor includes a spindle motor rotor or hub that is rotatably coupled to the disk drive base. The rotor has an outer flange that supports one of the disks. Additional disks may be stacked and separated with spacers. The spindle motor further includes an annular magnet element and a stator. The magnet element is typically attached about the lowermost portion of the rotor below the flange. The magnet element consists of a predetermined number of N and S poles that are disposed alternately circumferentially about the magnet element. The stator includes an outer stator rim that is attached to the disk drive base and a plurality of internally facing stator teeth. The stator teeth are equally spaced and extend from the stator rim. The stator is sized to fit about the rotor and in particular the magnet element. Each stator tooth includes windings that are oriented vertically about each of the stator teeth. The windings selectively conduct current to create a magnetic field that interacts with the various poles of the magnet element. Such interaction results in forces applied to the rotor that tend to rotate the rotor.
A topic of concern is the desire to reduce the overall disk drive size. Such disk drives may have a variety of applications such as in hand held or portable electronic devices. The exterior size and shape of the disk drive is often referred to as a xe2x80x9cform factorxe2x80x9d. Reduction of such disk drive form factor has proven challenging. This is because the mere reduction of the size of the various disk drive components may result in such components being unable to conform to required specifications.
One particular area of focus is the reduction of the height of the disk drive. It is contemplated that the spindle motor of a disk drive may become a limiting factor in the overall sizing of the disk drive height. The mere reduction in vertical sizing of the spindle motor components, such as the stator teeth, however, would directly reduce the flux density associated with the stator motor that may be below acceptable specifications. In addition, magnetic fields associated with adjacent stator teeth tend to negatively impact each other .(i.e., magnetic leakage) due to their relatively close proximity. Accordingly, there is a need in the art for an improved spindle motor configuration in comparison to the prior art.
An aspect of the invention can be regarded as a spindle motor for use in a disk drive. The spindle motor includes a spindle motor rotor and a stator. The spindle motor rotor defines a central axis. The spindle motor rotor includes a first plate defining a circular first plate periphery disposed about the central axis, a second plate defining a circular second plate periphery disposed about the central axis, and a magnet defining a circular periphery disposed about the central axis between and parallel to the first and second plates. The stator includes a plurality of magnetic flux guides distributed radially about the spindle motor rotor. Each magnetic flux guide includes a U-shaped guide body, a first end extending from the guide body and terminating at a first tooth face disposed adjacent the first plate periphery, and a second end extending from the guide body opposite the first end and terminating at a second tooth face disposed adjacent the second plate periphery. The second end is angularly off-set about the central axis with respect to the first end. The stator may further include windings disposed about each of the U-shaped guide bodies. The windings may be horizontally disposed. In the manufacturing of the magnetic flux guides, the individual guides may be formed from a single piece of material. In an embodiment, each tooth face may include multiple tooth faces.
According to another aspect of the present invention, there is provided a spindle motor for use in a disk drive. The spindle motor includes a spindle motor rotor and a stator. The spindle motor rotor defines a central axis. The spindle motor rotor includes a first plate defining a circular first plate periphery disposed about the central axis, a second plate defining a circular second plate periphery disposed about the central axis, and a magnet defining a circular periphery disposed about the central axis between and parallel to the first and second plates. The stator includes a plurality of magnetic flux guides distributed radially about the spindle motor rotor. Each magnetic flux guide includes a U-shaped guide body, a first end extending from the guide body and terminating at a first tooth face disposed adjacent the first plate periphery, and a second end extending from the guide body opposite the first end and terminating at a second tooth face disposed adjacent the second plate periphery. The second end is radially off-set from the central axis with respect to the first end. The stator may further include windings disposed about each of the U-shaped guide bodies. The windings may be horizontally disposed. In the manufacturing of the magnetic flux guides, the individual guides may be formed from a single piece of material. In an embodiment, each tooth face may include multiple tooth faces. In addition, the second end of each of the magnetic guide bodies may be angularly off-set about the central axis with respect to the first end.
According to another aspect of the present invention, there is provided a spindle motor for use in a disk drive. The spindle motor includes a spindle motor rotor and a stator. The spindle motor rotor defines a central axis. The spindle motor rotor includes a first plate defining a circular first plate periphery disposed about the central axis, a second plate defining a circular second plate periphery disposed about the central axis, and a magnet defining a circular periphery disposed about the central axis between and parallel to the first and second plates. The stator includes a plurality of magnetic flux guides distributed radially about the spindle motor rotor. Each magnetic flux guide includes a U-shaped guide body, a first end extending from the guide body and terminating at a first tooth face disposed radially adjacent the first plate periphery, and a second end extending from the guide body opposite the first end, horizontally overlapping with the second plate and terminating at a second tooth face disposed adjacent the second plate periphery. The first end and the first plate define a vertical gap. The second end and the second plate define a horizontal gap. The stator may further include windings disposed about each of the U-shaped guide bodies. The windings may be horizontally disposed. In the manufacturing of the magnetic flux guides, the individual guides may be formed from a single piece of material. In an embodiment, each tooth face may include multiple tooth faces. In addition, the second end of each of the magnetic guide bodies may be angularly off-set about the central axis with respect to the first end. The second end of each of the magnetic guide bodies may be radially off-set with respect to the first end.
In addition, according to other aspects of the present invention, the above described spindle motors may be included in a disk drive. Each such disk drive includes a disk drive base with the rotor rotatably coupled to the disk drive base and the stator attached to the disk drive base.